Plasmodium falciparum: selenium-induced cytotoxicity to P. falciparum.

The in vitro antimalarial activity of sodium selenite (NaSe) was investigated and the mechanism of its action was studied. NaSe had antimalarial activity against both the chloroquine-susceptible strain FCR-3 and chloroquine-resistant strain K-1 of Plasmodium falciparum. The shrunken cytoplasm of the parasite was observed in a smear 12 h after treatment with NaSe. Co-treatment with copper sulfate (CuSO(4)) in culture did not affect the antimalarial activity of NaSe, but NaSe cytotoxicity against the mammalian cell line Alexander was decreased significantly. The intracellular reduced glutathione level of parasitized red blood cells was decreased significantly by treatment with NaSe, and the decrease was consistent with their mortality. Treatment with NaSe had a strong inhibitory effect on plasmodial development, and NaSe cytotoxicity to human cells was decreased by co-treatment with CuSO(4). These results suggest that co-treatment with NaSe and CuSO(4) may be useful as a new antimalarial therapy.